new object or more geometry for detail?
This is really a personal preference thing. I personally dislike appending objects because it often ruins the loops of the mesh. The ugliness of the mesh is fixable by point manipulation. you can drag the points to move them into places that look better. another thing that might help with that is the "adjust cage to modifier result" Basically it makes the lines appear as if they are actually on the subdivided mesh, making point manipulation a lot easier to visualize. I used this when making a face model, it saved me a ton of time.